Censorship on China's Twitter

Censorship on Weibo, China’s version of Twitter, is near real-time and relies on a workforce of over 4,000 censors...

The Chinese version of Twitter is a microblogging service called Weibo which launched in 2010. This allows users to post 140 character messages with @usernames and #hashtags, just like Twitter– although 140 characters in Chinese contain significantly more information content than in English.

In just three years, Weibo has picked up some 300 million users who between them send 100 million messages each day at the rate of 70,000 per minute. That makes the inevitable process of censorship a tricky task for the Chinese authorities. So an interesting question is how they do it.

... in their data set about 5 per cent of the deletions occur within 8 minutes of posting and around 30 per cent within 0 minutes. In total, 90 per cent of deletions occur within a day, although at times deletions can occur several days later.

Wallach and co say their data point to a number hypotheses about what’s going on. Since the highest volume of deletions occur within 5-10 minutes of posting, Weibo must be censoring them in near real time. If an average censor can scan around 50 posts a minute, that would require some 1400 censors at any instant to handle the 70,000 posts pouring in. And if they work 8 hour shifts, that’s a total of 4200 censors on the payroll each day.